(a) Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly, to an LCD and a manufacturing method thereof that measures stitch errors between the panel shots for arrangement of the same when an LCD panel is formed by dividing the same into a plurality of shots.
(b) Description of the Prior Art
When exposing an active area (a display area) of the LCD panel in the case where the active area is larger than a mask, the active area is first divided into shots, and a step and repeat process of a stepper method is utilized. However, in the actual division of the active area into shots, a shifting, a rotation, a distortion and other flaws occur in the mask manufacturing and installation processes. This causes differences in parasitic capacitances between each line and pixel electrode in spaces between the panel shots, and differences in positions of patterns. Such differences in parasitic capacitances, in turn, result in variations in electrical characteristics of the LCD panel, while differences in positions of patterns result in discrepancies in effective aperture ratios.
In the manufacturing process of the thin film transistor (TFT) LCD--generally comprised of a plurality of layers such as a metallic layer, insulation layer, semiconductor layer, etc.--since layers, starting with a second layer, are stacked on a first layer, errors can be measured based on the first layer. However. since the first layer is not stacked on any layer, stitch verniers are provided in the LCD panel to measure errors in the first layer and the panel shots are arranged using this measured value.
Referring to FIG. 1, shown is a view illustrating a prior art LCD panel having stitch verniers. As shown in the drawing, an active area 10 of the LCD panel is divided into four shots A1, A2, A3 and A4. Dotted lines in the drawing indicate boundary lines, i.e. stitch lines, between the shots A1, A2, A3 and A4. Stitch verniers 14, for measuring misalignment of the panel shots A1, A2, A3 and A4 (stitch errors), are formed on a periphery 12 of the active area 10. Here, the disposing of the stitch verniers 14 on the periphery 12 of the active area 10, rather than within the same, is done to prevent a reduction in an effective aperture ratio of the LCD panel.
Referring now to FIG. 2, shown is a view of a prior art mask for exposing the LCD panel of FIG. 1. As shown in the drawing, the mask 20 comprises a mask shot 16 for exposing the panel shots A1, A2, A3 and A4 of the LCD panel, and vernier patterns s1, s2 s3 and s4 for exposing the stitch verniers 14 of the LCD panel. The vernier patterns s1, s2, s3 and s4 are detached at a predetermined distance (p) from the mask shot 16 such that a blind is formed to shield part of the mask 20 during exposure of the LCD panel. Without the formation of such a blind, the active area of the LCD panel is reduced.
That is, if the panel shot A1 of FIG. 1 is exposed using the mask 20 of FIG. 2 without blinding an active area of the panel shot A1, as vernier pattern s4 exposes an active portion of panel shot A4, the effective aperture ratio of the LCD panel is reduced. Accordingly, exposure is performed after the vernier pattern s4 is blinded so that the same is not exposed in the active area. For this reason, each vernier pattern s1, s2, s3 and s4 is distanced from outer boundaries of the mask shot 16 to the predetermined distance (p).
In the above, as the vernier patterns must be formed in areas where there are no patterns, such as areas corresponding to lines, a pad portion, etc., the distance between the mask shot and vernier patterns must be further increased.
However, as there is a limit to the size of the mask, the size of the mask shot becomes smaller as the distance between the same and the vernier patterns increases. As a result, the LCD panel must be divided into more numbers of mask shots for exposure such that exposure time is increased. This problem is further compounded by the fact that the blind positions must be repeatedly re-established when using the same mask for multiple exposure processes.
Further, as the stitch verniers are formed in the periphery of the active area, when a shifting, a rotation, a distortion and other flaws occur, as these defects of the peripheral portion of the active area and stitch lines do not correspond, flaws of the active area can not be precisely measured.